Closure for containers and device utilizing such closure

ABSTRACT

A tear-away closure is in form of a member of synthetic plastic which is to be fluid-tightly connected with a wall of a container, spanning an opening therein. An annular marginal portion of the member surrounds an aperture and is provided at that axial side thereof which will normally face the interior of the container with circumferentially spaced coupling portions which can engage with cooperating coupling portions on an auxiliary element with which the container is to be connected via the closure member. An inner portion of the member is located within the confines of the annular marginal portion and spans the aperture thereof in the region of the other axial side of the aperture. An annular weakened portion is unitary and fluidtightly connects the inner and annular marginal portions and comprises first and second circumferentially spaced arcuate sections which are respectively located on an inner and an outer imaginary circle, and third sections which extend at least substantially normal to and connect each second section with two adjacent first sections to define at circumferentially spaced locations a plurality of radial notches which are to afford access to the coupling portions. A gripping portion is in form of a strip of the inner portion which is bounded at its lateral sides by weakened lines one of which merges with the annular weakened portion, and a ring-shaped part of the strip projects from the inner portion and is to be engaged by the fingers of a user.

United States Patent Kuckens [151 3,661,306 51 May 9,1972

[54] CLOSURE FOR CONTAINERS AND DEVICE UTILIZING SUCH CLOSURE Alexander Kuckens, Bellevue 20, 2 Hamburg, 39, Germany 221 Filed: Dec. 16,1970

21 Appl.No.: 98,766

[72] Inventor:

Related US. Application Data [63] Continuation-impart of Ser. No. 6,670, Jan. 21, 1970.

Primary Evaminer-Stanley l-l. Tollberg Armrne v-Michael S. Striker 57 ABSTRACT A tear'away closure is in form of a member of synthetic plastic which is to be fluid-tightly connected with a wall of a container, spanning an opening therein. An annular marginal portion of the member surrounds an aperture and is provided at that axial side thereof which will nonnally face the interior of the container with circumferentially spaced coupling portions which can engage with cooperating coupling portions on an auxiliary element with which the container is to be connected via the closure member. An inner portion of the member is located within the confines of the annular marginal portion and spans the aperture thereof in the region of the other axial side of the aperture. An annular weakened portion is unitary and fluid-tightly connects the inner and annular marginal portions and comprises first and second circumferentially spaced arcuate sections which are respectively located on an inner and an outer imaginary circle, and third sections which extend at least substantially normal to and connect each second section with two adjacent first sections to define at circumferentially spaced locations a plurality of radial notches which are to afford access to the coupling portions. A gripping portion is in form of a strip of the inner portion which is bounded at its lateral sides by weakened lines one of which merges with the annular weakened portion, and a ring-shaped part of the strip projects from the inner portion and is to be engaged by the fingers of a user.

10 Claims, 3 Drawing Figures PA'TENTEDMM 91972 INVENTOR M M Mww TTORNEY CLOSURE FOR CONTAINERS AND DEVICE UTILIZING SUCH CLOSURE CROSS-REFERENCE TO RELATED APPLICATION A related application, of which the present one is a continuation-impart, Ser. No. 6,670, was filed on Jan. 2 l 1970 in my name under the title DISPENSING APPARATUS FOR LIQUIDS" and is currently copending.

BACKGROUND OF THE INVENTION The present invention relates generally to closures, and more particularly to closures for openings in containers and other vessels. Still more specifically the invention relates to a tear-away closure and to a device utilizing such a closure.

In my aforementioned copending application I have disclosed'a dispensing apparatus for liquids in which an electromagnetically operable liquid-dispensing device is provided having an inlet which is provided with screwthreads. The liquid to be dispensed by this device is provided in disposable liquid-containing tanks which are formed in a bottom wall thereof with an opening bounded by an internal circumferential surface provided with threads which are to mate with the threads on the dispensing device. The opening in the bottom wall of the tank is covered by a tear-away closure and fluid-tightly closed thereby, with the threads in the opening being concealed while the closure is in place. The closure is torn away when the tank is to be used, and then the threads on the tank are brought in mesh with the threads on the dispensing device whereby liquid from the tank can now enter the dispensing device and be dispensed by the latter. When the tank is empty it is unthreaded and replaced with a filled new one.

The closure, which actually is a member defining not only the opening provided with screwthreacls, but also a cover portion spanning this opening until it is torn away, is of synthetic plastic material for various reasons, one of these being that the plastic material can be readily torn when the closure is to be opened and another reason being that the plastic material is intended to provide a sealing function as its threads mesh with those on the dispensing device.

While my invention as disclosed in the aforementioned copending application provides substantially advantages over what is known from the art, it does have a drawback which is not to be overlooked. Specifically, when the threads in the synthetic plastic material of the closure mesh with the threads on the dispensing device, which may or may not also be of synthetic plastic material, the danger exists that they will not properly move into mesh. However, because of the character of the material involved this does not preclude engagements of the threads with one another; instead, the threads will simply overlap rather than be in mesh. This is a problem which occurs quite frequently where threads are provided in synthetic plastic material and which frequently cannot be avoided even with the most careful handling. The self-evident disadvantage of this is that if the problem occurs, the sealing function which is required to prevent leakage of liquid at the juncture between the tank and the dispensing device, is lost and consequently much or all of the liquid from the tank may be wasted. Other disadvantages obtain also, of course, including the fact that bacteria may enter at this improper connection.

The problem thus presents itself how to obtain the desirable advantages of a tear-away closure utilizing synthetic plastic, that is the self-sealing function which it can afford as well as the ready tearing of the material when the closure is to be opened, without having to accept the aforementioned disadvantages.

SUMMARY OF THE INVENTION It is, accordingly, an object of the'present invention to provide such an improved tear-away closure.

An additional object of the invention is to provide such an improved tear-away closure which is simple in its construction and inexpensive to make.

A concomitant object of the invention is to provide a liquiddispensing apparatus utilizing the improved tear-away closure.

In pursuance of the above objects, and others which will become apparent hereafter, one feature of the invention resides, briefly stated, in a closure for openings of tanks and other containers which comprises an annular wall portion adapted for fluid-tight connection to the wall of a container bounding an opening therein, such wall portion surrounding an aperture having two axial sides one of which faces the interior of the container when the wall portion is connected to the same. Circumferentially spaced coupling portions are provided on the annular wall portion in the region of the aforementioned one side for engagement with cooperating coupling portions on an auxiliary element, such as a liquid-dispensing device. An inner wall portion is located within the confines of the annular wall portion and spans the aperture therein in the region of the other of the axial sides. An annular weakened portion is unitary with and fluid-tightly connects the inner and annular wall portions; it comprises first and second circumferentially spaced arcuate sections respectively located on an inner and an outer imaginary circle and third sections extending at least substantially normal to and connecting each second section with two adjacent first sections so as to define at circumferentially spaced locations of the annular weakened zone radial notches for affording access to the coupling portions. A gripping portion is of one piece with the wall portions and arranged to be gripped by a user so that, upon exertion of requisite pull on the gripping portion, the inner wall portion is separated from the outer wall portion along the sections of the weakenedportion, opening the aperture as well as the notches and thus affording access through the latter to the coupling portions.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims.

The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary sectional elevational view showing a portion of a tank provided with my novel closure;

FIG. 2 is a perspective view of the underside of FIG. I, that is looking upwardly in FIG. 1; and

FIG. 3 is a fragmentary perspective view, partially in section and partially broken away, of a dispensing apparatus utilizing the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing in detail, and firstly FIGS. 1 and 2 thereof, it will be seen that I have illustrated therein one embodiment of my novel tear-away closure. Reference numeral 1 identifies the somewhat diagrammatically shown circumferential wall of a container, which wall bounds an opening. It will be appreciated that the container will normally be filled with a substance, usually liquid, which is to be prevented from exiting through this opening, and from contact with the ambient atmosphere until such time as it is intended to purposely open the container.

For this purpose the opening is closed by my novel closure, which is identified in tote with reference numeral 3. It may include a wall portion 2 connected with the circumferential wall 1 of the container, or the wall portion 2 may be part of the container wall 1, whether integral therewith or separately secured thereto, but in either case my tear-away closure will be fluid-tightly connected with the wall portion 2 in the manner illustrated or in another suitable manner. This is not a part of the present invention, it being evident that such a fluidtight connection can be accomplished in various different ways.

The actual closure member consists of synthetic plastic material, different ones of which are suitable for the purpose, and comprises an outer annular portion 4 which is that part of the closure that is fluid-tightly connected with the wall portion 2. Located within the confines of the outer annular portion 4-which latter surrounds an aperture 4ais an inner wall portion which spans this aperture at one axial end of the latter, namely that axial end which when the closure is provided on a container as illustrated in FIG. 1, will face outwardly away from the interior of the container. The wall portions 4 and 5 are fluid-tightly connected with one another by a weakened annular portion 6 which is of one piece with them both.

This weakened annular portion 6 extends circumferentially of the aperture 4a as most clearly shown in FIG. 2, where it is illustrated in dotted lines and as FIG. 1 shows the portion 6 may be provided by scoring, pressing or otherwise weakening the material ofthe closure 3.

In accordance with the present invention the weakened portion 6 is composed of a plurality of first arcuate sections 6a located on an imaginary inner circle and circumferentially spaced from one another as shown. A further plurality of sections 6b are located on an imaginary outer circle surrounding the inner circle (compare FIG. 2) and register with the gaps defined between the ends of circumferentially adjacent ones of the first sections 6a. It should be pointed out, parenthetically, that both the sections 60 and the sections 617 may be but need not be arcuate. Each of the sections 6b is connected with the ends of the two sections 6a with which it cooperates, by two sections 60 which extend transversely of the sections 6a and 6b either at a right angle or at an inclination which may closely approach a right angle to the sections 6a and 6b. In other words, where the sections 60 merge with the sections 6a and 6b, respectively, the junctures are quite sharp rather than of pronouncedly rounded configuration. This is clearly shown in FIG. 2.

The cooperating sections 611,6!) and 6c thus define with one another radial notches 9 which, in the illustrated embodiment, extend radially outwardly and of which there are four shown although there could be more or fewer of them.

The possibility of providing these notches 9 in a tear-away closure, with the sharp changes of directions at the junctures of the sections 60 and 6c on the one hand, and the sections 6c and 6b on the other hand, is unique to the use of synthetic plastic material because in metallic material such sharp changes of directions in a tear-away closure would not be possible, at least not without causing deformation of the metallic material at these junctures.

The junctures are important, however, because according to the present invention the coupling which permits coupling of the closure 3 with an auxiliary element, such as the liquiddispensing device which is to be discussed more fully with reference to FIG. 3, is to be ofthe bayonet type and not to utilize screwthreads because of the disadvantages of screwthreads which have been-outlined in the introductory portion of this specification. For bayonet type of closures, however, it is essential that the notches 9 be provided and that the junctures between the various sections 6a, 6b and 6c be as clean and as abrupt as possible.

To permit opening of the closure, that is to permit tearingaway of the portion 5 from the portion 4, I provide a gripping portion which is clearly shown in FIGS. 1 and 2. The provision of this particular gripping portion also departs from what is known in the art. Conventionally such gripping portions extend circumferentially of the opening which is closed by the tear-away closure and pull exerted on them is exerted in circumferential direction. However, it has been found that quite frequently a user is not certain in which circumferential direction he is to exert pull, that is whether towards the left or towards the right. This is avoided according to the present invention by having the tear-away or gripping portion extend transversely of the aperture 4a substantially radially of the outline of the weakened portion 6, as evident from FIG. 2 in particular. From the location of the ring-shaped part of the gripping portion, through which a user will normally insert a finger to exert a pulling action, it is clear that pull is intended to be exerted in only one direction, namely from the left towards the right in FIG. 2 and of course upwardly at the same time. The gripping portion according to the present invention comprises not only the ring-shaped part 8 but a strip-shaped part 7 which is a part of the inner portion 5 itself and is outlined or bounded by two scoring lines or weakened lines 12 shown in FIG. 2 in dot-dash lines, with one of them merging with the weakened zone 6, or more particularly with one of the sections 6a thereof. The part 8 is of course fast with the strip-shaped part 7 and when it is pulled upwardly the stripshaped part 7 will first be severed from the remainder of the portion 5 along the weakened lines 12. When the curved juncture of the one weakened line 12 with the one section 6a (see FIG. 2) is reached, the pulling force will be channeled and diverted in a direction at an angle to the previous one. Now, severing of the portion 5 from the portion 4 begins first along the initial section 6a, then at an almost right angle relative to the initial section 6a along the first section 6c, then again at an almost right angle along the first section 6b, again at an almost right angle to the previous direction along the second section 6c, and again at an almost right angle to the previous direction along the next section 6a. This continues until the portion 5 is completely detached from the portion 4 along the weakened annular portion 6.

The severed part of the closure 3 is now discarded and the aperture 4 is exposed. The notches 9 in this condition afford access to the coupling portions which are located in the illustrated embodiment (see FIG. 1) at the opposite or inner axial side of the aperture 5a. These coupling portions in the illustrated embodiment are in form of circumferentially inclined guide faces 10 which terminate in depressions 11 and it will be clear that if in the manner of a bayonet closure of conventional type, a part of an auxiliary element provided with corresponding coupling projcctions is extended into the opening 4a so that the coupling projections each move through one of the notches 9, a relative rotational displacement between the closure and the coupling projections of the auxiliary element will cause the coupling projections to ride up on the inclined guide faces 10 and to snap into the recesses 11, thus providing a reliable coupling which, because it does not utilize screwthreads, is not possessed of the disadvantages which have been outlined in the introductory portion of the specifcation.

FIG. 3 shows an apparatus utilizing my novel closure. In this FIG., reference numeral 14 identifies an electromagnetically operable liquid dispensing device of the general type discussed in my aforementioned application and also in my U. S. Pat. No. 3,258,166. Specific details concerning the construction and operation of the device 14 may therefore be obtained from either of these sources.

As the drawing shows, the device 14 comprises an inner portion 15 having substantially inverted cup-shaped configuration and extending through the aperture 4a (see FIG. 2) which is already open into the interior of the receptacle 1. The latter may consist of sheet metal or another suitable material of requisite mechanical strength. The portion 15 is provided with coupling projections 13 (one shown) which each extend through one of the notches 9 and which serve to ride up on the respective guide faces 10 and to snap into a cooperating recess 11 in the manner discussed above. These coupling projections 13 therefore constitute, together with the components 10 and 11, a bayonet type of coupling.

The portion 15 is provided with an opening 16 through which liquid can enter into the interior of the portion 15 from the interior of the receptacle 1, and through which opening air can escape from the portion 15 to the interior of the receptacle 1. A venting bore 17 is provided in the device 14 and communicates with a similar bore or suitable conduit provided in the interior of the portion 15, with the latter bore or conduit being identified with reference numeral 18 and having a free open end located closely adjacent the transverse wall 19 of the portion 15.

The device 14 comprises a second portion which is located exteriorly of the receptacle 1 and which includes two cylindrical sections 22 and 23, with the former having a smaller diameter than the latter. There is further provided a conically tapering intermediate section 21 located between the sections 22 and 23. A vertically reciprocable magnetizable armature 24 is guided in the cylindrical section 23 and provided with an annular circumferential head which engages the inner circumferentially tapered surface of the conically tapering section 21 under the influence of gravity, namely the weight of the armature 24, when the latter is not magnetized. In this case the bead, having reference numeral 25 in FIG. 3, seals the device and prevents the outflow of liquid through-the outlet opening in the direction of the arrow shown in FIG. 3.

The upper portion of the section 23 is exteriorly surrounded by a coil 26 which is connected in series with a source of electrical energy 28 via conductors 27. A timer of any known construction is interposed in the electrical circuit 26, 27 and 28 and may either be closed manually by means of the actuating portion 30, such as a pushbutton or the like, or it may be closed for a predetermined period of time by insertion of a coin of given denomination. Such timers are well known in the vending machine art and need not be specifically described here, particularly because a more detailed discussion may be found in my aforementioned U. S. Pat. No. 3,258,166.

In operation of the apparatus shown in FIG. 3, and assuming that the device 14 is to be provided for the first time with a liquid-filled container, or that a previous container has been emptied and is to be replaced with a new filled container-the new container is placed onto a support with the wall portion 2 facing upwardly. Now, the user inserts a finger or tool through the portion 9 of the closure and exerts pull in the direction of the arrow shown in FIG. 2, thereby severing the wall portion 5 from the wall portion 4 along the weakened portion 6. This frees the aperture 4a and the notches 9. Once this has occurred, the coupling portions 10, 11 are accessible. Now, the device 14 is connected with the container 1, or rather with the closure 3 thereof, in the manner already discussed, namely in the manner of a bayonet coupling, and at this time the total structure will have the appearance shown in FIG. 3 but as seen if FIG. 3 were turned through 180", namely upside-down from what is illustrated. Now, the structure can be turned over to the position shown in FIG. 3 with the outlet 20 facing downwardly, because as soon as such turning takes place the member 24 will descend under the influence of gravity and a seal will be established by the bead 25 in the section 21.

When a portion of the contents of the tank 1 is to be dispensed, the electric circuit 26, 27 and 28 is energized by means of a timer 29, resulting in energization of the coil 26 and magnetizing of the armature 24 which is thereby lifted by the magnetic field of the coil 26 to the illustrated broken-line position. In this position it is retained as long as the coil 26 remains energized and during this period of time liquid can issue from the interior of the receptacle 1 through the opening 16 into the portion 15 and from there via axially extending grooves 31 provided for this purpose in the outer circumferential surface of the armature 24 and through the outlet 20. If the starting pressure in the device decreases as a result of the issuance of liquid, air enters from the ambient atmosphere through the bore 17 and the bore or conduit 18 and passes through the aperture 16 into the interior of the receptacle 1 where it rises in form of air bubbles into the space above the liquid level. This space is completely closed with reference to the ambient atmosphere except for the entry of such air bubbles.

After a predetermined period of time the timer 29 interrupts the electric circuit, permitting the magnetic field to collapse and the now demagnetized armature 24 to descent under the influence of its own weight and gravity action to the fullline position in FIG. 3, where it againseals the device 14 against the escape ofliquid.

Naturally, the device herein illustrated may be used with liquid of any desired viscosity. The accuracy of dispensing of desired quantities is very high, even if the liquids are highly viscous such as syrups, so that even for such liquids a high accuracy and speed of dispensing can be achieved, an advantage to those already outlined above.

Naturally, various modifications over the exemplary embodiments illustrated are possible and are intended to be fully encompassed within the scope and context of the present invention. Thus, sealing means can be additionally provided for establishing an additional seal between the receptacle 1 and the device 14 when the coupling portions 13 of the device 14 mate with the coupling portions 10, 11 on the closure 3. Sealing means of this type are for instance disclosed in my aforementioned copending application. It is also possible to locate the coupling portions 10 and 11 in a manner different from what has been illustrated. They could be located closer to but still inwardly of the portion 5 ifdesired. As pointed out before, different types of synthetic plastic materials may be used, and all such types which are suitable and which will offer themselves readily to those having ordinary skill in the art, are to be considered encompassed within the scope and concept of the present invention.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a tear-away closure and apparatus utilizing the same, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. In a dispensing apparatus for liquids, in combination, a disposable liquid-containing tank having a wall provided with an opening; an electromagnetically operable liquid-dispensing device having an inlet; first coupling means on said dispensing device and including a plurality of coupling projections spaced circumferentially of said inlet; second coupling means, including coupling portions engageable with said projections, on said tank in the region inwardly of said opening; and tear-away closure means on said opening, including a closure member spanning said opening and having an annular marginal portion fluid-tight with said wall, an inner portion within said marginal portion, an annular weakened portion connecting said inner portion with said marginal portion and comprising first and second circumferentially spaced sections respectively located on an inner and an outer imaginary circle and third sections connecting each secondsection with two adjacent first sections extending at least substantially normal thereto and defining therewith at circumferentially spaced locations radial notches which afford access to said coupling portions, and a gripping portion arranged to be gripped by a user for separating said inner and marginal portions along said weakened portion in response to exertion of requisite force on said gripping portion.

2. In a dispensing apparatus as defined in claim 1, wherein said closure member consists of synthetic plastic material.

3. In a dispensing apparatusas defined in claim 2, wherein said gripping portion is at least in part ring-shaped.

4. In a dispensing apparatus as defined in claim 2, wherein said gripping portion comprises a strip-shaped part of said inner portion extending across the latter substantially radially of said marginal portion and bounded by respective lateral weakened lines one of which merges with said weakened portion, and a ring-shaped part fast with said strip-shaped part for engagement by a user.

5. In a dispensing apparatus as defined in claim 2, wherein said third sections extend substantially at right angles to the respectively associated first and second sections.

6. As a novel article of manufacture, a closure for openings of tanks and other containers, comprising an annular wall portion adapted for fluid-tight connection to the wall bounding an opening in a container, said wall portion surrounding an aperture having two axial sides one of which faces the interior of the container when said wall portion is connected to the same; circumferentially spaced coupling portions on said annular wall portion in the region of said one side for engagement with cooperating coupling portions on an auxiliary element; an inner wall portion within the confines of said annular wall portion and spanning said aperture in the region of the other of said axial sides; an annular weakened portion unitary with sad fluid-tightly connecting said inner and said annular wall portions, said weakened portion comprising first and second circumferentially spaced sections respectively located on an inner and an outer imaginary circle and third sections extending at least substantially normal to and connecting each second section with two adjacent first sections so as to define at circumferentially spaced locations of said annular weakened zone radial notches for affording access to said coupling portions; and a gripping portion of one piece with said wall portions and arranged to be gripped by a user for separating said inner wall portion from said outer wall portion along said sections of said weakened portion in response to exertion of requisite pull by a user.

7. An article of manufacture as defined in claim 6, wherein said portions consist of synthetic plastic material.

8. An article of manufacture as defined in claim 7, said third sections defining with the respective first and second sections at least three equidistantly spaced ones of said radial notches.

9. An article of manufacture as defined in claim 7, said coupling portions being constructed and arranged for cooperating with coupling portions of an auxiliary element in the manner of a bayonet coupling.

10. An article of manufacture as defined in claim 7, said gripping portion comprising a strip-shaped part of said inner wall portion extending across the latter substantially radially of said annular weakened portion and bounded by respective lateral weakened lines one of which merges with said weakened portion, and a ring-shaped part on said strip-shaped part for engagement by a user. 

1. In a dispensing apparatus for liquids, in combination, a disposable liquid-containing tank having a wall provided with an opening; an electromagnetically operable liquid-dispensing device having an inlet; first coupling means on said dispensing device and including a plurality of coupling projections spaced circumferentially of said inlet; second coupling means, including coupling portions engageable with said projections, on said tank in the region inwardly of said opening; and tear-away closure means on said opening, including a closure member spanning said opening and having an annular marginal portion fluid-tight with said wall, an inner portion within said marginal portion, an annular weakened portion connecting said inner portion with said marginal portion and comprising first and second circumferentially spaced sections respectively located on an inner and an outer imaginary circle and third sections connecting each second section with two adjacent first sections extending at least substantially normal thereto and defining therewith at circumferentially spaced locations radial notches which afford access to said coupling portions, and a gripping portion arranged to be gripped by a user for separating said inner and marginal portions along said weakened portion in response to exertion of requisite force on said gripping portion.
 2. In a dispensing apparatus as defined in claim 1, wherein said closure member consists of synthetic plastic material.
 3. In a dispensing apparatus as defined in claim 2, wherein said gripping portion is at least in part ring-shaped.
 4. In a dispensing apparatus as defined in claim 2, wherein said gripping portion comprises a strip-shaped part of said inner portion extending across the latter substantially radially of said marginal portion and bounded by respective lateral weakened lines one of which merges with said weakened portion, and a ring-shaped part fast with said strip-shaped part for engagement by a user.
 5. In a dispensing apparatus as defined in claim 2, wherein said third sections extend substantially at right angles to the respectively associated first and second sections.
 6. As a novel article of manufacture, a closure for openings of tanks and other containers, comprising an annular wall portion adapted for fluid-tight connection to the wall bounding an opening in a container, said wall portion surrounding an aperture having two axial sides one of which faces the interior of tHe container when said wall portion is connected to the same; circumferentially spaced coupling portions on said annular wall portion in the region of said one side for engagement with cooperating coupling portions on an auxiliary element; an inner wall portion within the confines of said annular wall portion and spanning said aperture in the region of the other of said axial sides; an annular weakened portion unitary with sad fluid-tightly connecting said inner and said annular wall portions, said weakened portion comprising first and second circumferentially spaced sections respectively located on an inner and an outer imaginary circle and third sections extending at least substantially normal to and connecting each second section with two adjacent first sections so as to define at circumferentially spaced locations of said annular weakened zone radial notches for affording access to said coupling portions; and a gripping portion of one piece with said wall portions and arranged to be gripped by a user for separating said inner wall portion from said outer wall portion along said sections of said weakened portion in response to exertion of requisite pull by a user.
 7. An article of manufacture as defined in claim 6, wherein said portions consist of synthetic plastic material.
 8. An article of manufacture as defined in claim 7, said third sections defining with the respective first and second sections at least three equidistantly spaced ones of said radial notches.
 9. An article of manufacture as defined in claim 7, said coupling portions being constructed and arranged for cooperating with coupling portions of an auxiliary element in the manner of a bayonet coupling.
 10. An article of manufacture as defined in claim 7, said gripping portion comprising a strip-shaped part of said inner wall portion extending across the latter substantially radially of said annular weakened portion and bounded by respective lateral weakened lines one of which merges with said weakened portion, and a ring-shaped part on said strip-shaped part for engagement by a user. 